### 1.通过IRule实现修改负载均衡规则



![image.png](/static/img/4b100f0290b6f5a42cf8148efbfa9a40.image.webp)

```java
@MapperScan("cn.itcast.order.mapper")
@SpringBootApplication
public class OrderApplication {

    public static void main(String[] args) {
        SpringApplication.run(OrderApplication.class, args);
    }

    @Bean
    @LoadBalanced
    public RestTemplate restTemplate(){
        return new RestTemplate();
    }

    @Bean
    public IRule randomRule(){
        return new RandomRule();
    }
}
```
### 2.饥饿加载

![image.png](/static/img/fab608c523985b326c56b7459fbfc2f5.image.webp)

```config
ribbon:
  eager-load:
    enabled: true #开启饥饿加载
    clients:  # 指定饥饿加载的服务名称
      - userservice
```

配置Ribbon负载均衡

# **eurek**


## (1)搭建eureka注册中心

### 1.引入eureka注册中心的依赖
![](https://qianxiaojie.xyz/static/img/fa505c62de190b8e0515cd70dff12ebc.image.webp)

```pom
<dependency>
           <groupId>org.springframework.cloud</groupId>
           <artifactId>spring-cloud-starter-netflix-eureka-server</artifactId>
</dependency>
```
### 2.编写启动类添加@EnableEurekaServer注解
![](https://qianxiaojie.xyz/static/img/073c41ef142568c6aa2952da985b5ecb.image.webp)
### 3.添加application.yml文件

```config
server:
  port: 10086
spring:
  application:
    name: eurekaserver
eureka:
  client:
    service-url:
      defaultZone: http://127.0.0.1:10086/eureka
```
## (2)注册服务(user-server)
### 1.在user-server服务中引入依赖

```pom
<dependency>
            <groupId>org.springframework.cloud</groupId>
            <artifactId>spring-cloud-starter-netflix-eureka-client</artifactId>
</dependency>
```
### 2.在user-sever的application.yml中添加配置

```config
spring:
  application:
    name: userservice
eureka:
  client:
    service-url:
      defaultZone: http://127.0.0.1:10086/eureka
```
### 3.启动全部服务查看eureka中是否显示

![image.png](/static/img/29a27e7bf79444a65cfc142299af1a17.image.webp)
## (3)在order-server中实现服务拉取
### 1.使用服务名称代替服务ip和端口

```java
@GetMapping("{orderId}")
    public Order queryOrderByUserId(@PathVariable("orderId") Long orderId) {
        // 根据id查询订单并返回
        Order order = orderService.queryOrderById(orderId);
        // 利用RestTemplate发送http请求
        String url = "http://userservice/user/"+order.getUserId();
        User user = restTemplate.getForObject(url, User.class);
        // 封装User
        order.setUser(user);
        return order;
    }
```
### 2.实现负载均衡

![image.png](/static/img/61da44de69699ff9fd443c6f3c74be26.image.webp)

```java
@MapperScan("cn.itcast.order.mapper")
@SpringBootApplication
public class OrderApplication {

    public static void main(String[] args) {
        SpringApplication.run(OrderApplication.class, args);
    }

    @Bean
    @LoadBalanced
    public RestTemplate restTemplate(){
        return new RestTemplate();
    }
}
```